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Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc.


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  #1  
Old 11-16-2011, 03:53 PM
motohellrider motohellrider is offline
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Default Pistons worn out limit

Hi all,

I would like ask you about service limit for pistons.I have EC 300 R Nambotin.

Thanks for info..


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Old 11-16-2011, 07:09 PM
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Jakobi Jakobi is offline
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Are you looking for time frames ie. Engine hours? or specs? Ring gap, etc?

Generally you are looking at 50hrs - 100hrs for a 300. I did my first one at 75hrs. Ring gap was still middle of spec. Piston skirt was showing minimal wear. I did have some engine noise as revs fell which is why i went digging. It cleared up after new piston. I wouldn't be doing it before 75hrs and I tend to show the bike lots of revs. If you lug alot 100hrs easy.
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Old 11-17-2011, 01:53 AM
motohellrider motohellrider is offline
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I mean if there is some limit, for example new one has some dimensions and limit for change is this dimensions
Each rider has different styly, therofore should be some exactlly dimensions
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Old 11-17-2011, 02:23 AM
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I get what you're saying. Measurable data. The question is though if you're going to pull the bike down to the point that you can measure everything, would you not just throw a fresh top end in as cheap insurance?

As far as measurements go I'd say they would be the same as any other engine. Essentially its a nikasil coated cylinder running a normal 2 ring piston. Sorry I don't have any figures for you though.
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Old 11-17-2011, 07:42 AM
Rabbitist Rabbitist is offline
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For my 250 the ring gap is between .4mm bottom limit and .7mm top limit on the ring gap..think the 300's run slightly larger gaps off the top of my head..
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Old 11-17-2011, 09:42 AM
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If you do not have good instruments don't bother trying to measure the bore/piston to determine a clearance. If you run good oil and keep a clean filter, the ring wear will not be a factor. I run 75 - 100 hrs in a 250, compresion is still over 180 PSI, piston looks great through the ports with little to no blow by. I'm sure if I tore it down to measure it it would be in spec. I also run 36:1 premix. The next issue is fatigue of the aluminum. This is the limit you will eventually hit. If there is wear, increased clearance, and piston slap, this will be accelerated and the skirt can fail. For all the time it takes to tear down, clean, and measure parts, I'll do the complete top end swap at 75-100 hrs. I don't bother doing rings alone.
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Old 11-17-2011, 09:48 AM
lankydoug lankydoug is offline
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Quote:
Originally Posted by GMP View Post
If you do not have good instruments don't bother trying to measure the bore/piston to determine a clearance. If you run good oil and keep a clean filter, the ring wear will not be a factor. I run 75 - 100 hrs in a 250, compresion is still over 180 PSI, piston looks great through the ports with little to no blow by. I'm sure if I tore it down to measure it it would be in spec. I also run 36:1 premix. The next issue is fatigue of the aluminum. This is the limit you will eventually hit. If there is wear, increased clearance, and piston slap, this will be accelerated and the skirt can fail. For all the time it takes to tear down, clean, and measure parts, I'll do the complete top end swap at 75-100 hrs. I don't bother doing rings alone.
Do you prefer a cast or forged piston?
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Old 11-17-2011, 09:50 AM
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HuskyDude HuskyDude is offline
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Quote:
For all the time it takes to tear down, clean, and measure parts, I'll do the complete top end swap at 75-100 hrs. I don't bother doing rings alone.
Ya....what he said...
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Old 11-20-2011, 04:14 PM
motohellrider motohellrider is offline
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Hi all, today I?have done dissasembled of pistons. Ring gap is 0,65. Limit is0,8. Pistons look nice ańd I am going measure it. Also cylinder.

But?what is limit for pistons and cylinder?

thnaks
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Old 11-20-2011, 08:22 PM
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I like the Vertex cast pistons, have had great service life from them with no problems at a good price.
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